This invention relates broadly to the field of domestic water heating and domestic space heating and cooling. More specifically, the invention relates to an improved refrigeration circuit which is operative in various modes to heat a space; cool a space; heat domestic water as a priority without affecting space temperature; simultaneously heat domestic water and cool a space by desuperheating refrigerant vapor; and simultaneously heat domestic water and heat a space by desuperheating refrigerant vapor. In an alternative mode, the refrigeration circuit of this invention allows simultaneous heating of water and cooling a space by condensing refrigerant vapor.
It is, of course, known in the art to provide reversible heat pumps for heating or cooling air ducted to an interior space. It has also been proposed to combine the heating/cooling of air with domestic water heating in a single system. See, for example, U.S. Pat. No. 4,249,390 which provides for the heating of water while cooling a space, and heating of water while heating a space.
In U.S. Pat. No. 3,916,638, a heat pump is disclosed which may be used to cool a space, or to heat domestic water while cooling a space.
In U.S. Pat. No. 4,299,098, a refrigeration circuit is disclosed which is designed for operation in four modes: heating a space; cooling a space, heating water without affecting space temperature; and simultaneously heating water while cooling a space.
In U.S. Pat. No. 4,399,664, a refrigeration circuit is disclosed which adds a fifth function to those which are disclosed in U.S. Pat. No. 4,299,098, i.e., simultaneously heating water while heating a space.
The present invention relates to a refrigeration circuit which has five similar modes of operation, i.e., heating a space; cooling a space; heating water without affecting space temperature; simultaneously heating water while cooling a space; and simultaneously heating water while heating a space. In the present invention, however, an improved refrigeration circuit is provided which minimizes valving, refrigerant storage vessels, and associated controls necessary to obtain proper refrigerant control.
Thus, in one exemplary embodiment of the invention, a refrigeration circuit is provided which includes a conventional compressor which discharges refrigerant vapor to a conventional domestic water desuperheater/condenser. A three-way diverter valve lies downstream of the desuperheater/condenser, one port of which directs flow to a four way reversing valve. Both the diverter valve and reversing valve may be operated by conventional control means. The reversing valve is operative to direct refrigerant vapor flow to either an indoor evaporator/condenser unit or an outdoor evaporator/condenser unit (both of which may be of conventional construction) depending on operating mode. The indoor and outdoor evaporator/condenser units are also connected by a conduit which incorporates two pairs of restrictors or capillary tubes, one pair associated with each unit. Depending on operating mode, refrigerant will flow through one or both tubes of one or the other pairs of tubes via a suitable conduit arrangement. In addition, a pair of check valves are provided, one each of which is associated with the indoor evaporator/condenser and outdoor evaporator/condenser for bypassing the restrictors whenever refrigerant flow is in a direction out the indoor or outdoor evaporator/condenser units.
Refrigerant vapor from either the indoor evaporator/condenser or from the outdoor evaporator/condenser is returnable to the compressor by way of the reversing valve, a compressor suction conduit, an accumulator, and a pair of liquid conduit/suction conduit heat exchangers.
In an exemplary embodiment of the invention, domestic water may be diverted into and out of the desuperheater/condenser when it is desired to heat the water. The controls for so directing the domestic water supply are conventional and need not be described in detail.
It will further be appreciated that the refrigeration circuit of this invention may be employed to heat liquids other than domestic water, and in environments other than the domestic, or home, system described in detail herein.
In a first mode, for heating a space, no water is diverted into the desuperheater/condenser, and hot refrigerant vapor discharged through the domestic water desuperheater/condenser is diverted by the diverter valve to the reversing valve. The reversing valve directs the refrigerant flow to the indoor evaporator/condenser where the refrigerant vapor is condensed and heat is rejected to the space. The condensed (liquid) refrigerant then exits the indoor evaporator/condenser and flows through a first check valve to a first liquid conduit which incorporates a liquid conduit/suction conduit heat exchanger for subcooling of the liquid refrigerant. The liquid refrigerant then flows through one of the restrictors or capillary tubes and into the outdoor evaporator/condenser where the refrigerant liquid evaporates, absorbing heat. Refrigerant vapor exits the outdoor evaporator/condenser and flows back through the reversing valve to the compressor suction conduit and thereafter through the accumulator, first heat exchanger and finally, to the compressor.
In a second mode, where space is heated and domestic water is heated, the above-described flow path is utilized, but at the same time, water is passed through the desuperheater/condenser and is heated by desuperheating the refrigerant vapor.
In a third mode of operation, for cooling a space, again no water is diverted into the desuperheater/condenser. Hot refrigerant vapor discharged from the compressor passes through the water desuperheater/condenser to the diverter valve which directs the flow to the four way reversing valve which, in turn, directs the vapor to the outdoor condenser/evaporator. Refrigerant vapor here rejects heat to the air or to a water/ground sink and condenses. The refrigerant now in liquid form flows through a second check valve and through a liquid conduit, associated heat exchanger and through another of the restrictor or capillary tubes into the indoor evaporator/condenser, where the liquid evaporates, absorbing heat from the space. The refrigerant, which is now in cool vapor form, is then directed to the compressor suction conduit, through the accumulator, first heat exchanger and then finally to the compressor.
In a fourth, related mode, domestic water is heated while the space is cooled by diverting water through the desuperheater/condenser where, as in the second mode, refrigerant vapor is desuperheated, transferring excess heat to the water.
In a fifth mode, and upon a priority demand for domestic hot water, water may be heated without affecting the space temperature. When it is desired to heat the domestic water as a priority, appropriate and conventional controls are employed which permit heating of the water regardless of whether the system is otherwise operating in a heating or cooling mode, and without affecting space temperature. Thus, upon demand for domestic hot water, when the controls are otherwise in a space heating mode, the hot refrigerant vapor discharged by the compressor flows through the domestic water desuperheater/condenser where it is condensed, rejecting heat to the domestic water. The refrigerant is then directed to the diverter valve which directs the liquid refrigerant to the first liquid/suction heat exchanger where it is subcooled. The liquid then flows through a liquid conduit and the pair of series arranged restrictors or capillary tubes associated with the outdoor evaporator/condenser unit, and then into the outdoor evaporator/condenser where the refrigerant evaporates, absorbing heat. Refrigerant vapor then exits the outdoor evaporator/condenser and flows through the reversing valve and returns to the compressor via the accumulator and second liquid conduit/suction conduit heat exchanger. Excess liquid refrigerant is allowed to flow through the other set of restrictor tubes and into the indoor evaporator/condenser for temporary storage. As the demand for domestic hot water is satisfied, the diverter valve is reversed, returning the refrigerant circuit to the normal space heating mode and returning excess refrigerant stored in the indoor evaporator/condenser to the active refrigerant circuit.
Upon a priority demand for hot water when the controls are otherwise in a space cooling mode, the refrigerant flow circuit is as described immediately above with the understanding that as the demand for hot water is satisfied, the circuit is returned to a space cooling mode.
In a sixth and alternative operating mode, water is heated while the space is cooled, utilizing a flow path wherein the water is heated by refrigerant vapor condensation rather than desuperheating. Thus, refrigerant vapor from the compressor passes through the domestic water desuperheater/condenser where it is condensed and heat is rejected to the domestic water supply. The liquid is then diverted in the diverter valve to the second liquid conduit/suction conduit heat exchanger where it is subcooled. The liquid then flows through a liquid conduit and a pair of series arranged restrictor or capillary tubes associated with the indoor condenser/evaporator and then to the indoor condenser/evaporator unit itself. From the indoor evaporator/condenser, refrigerant vapor flows through a suction conduit to the compressor via the reversing valve, accumulator and second suction conduit/liquid conduit heat exchanger. In this mode of operation, excess liquid refrigerant is allowed to flow through liquid conduits to the outdoor condenser/evaporator where it is temporarily stored.
Additional objects and advantages of the present invention will become apparent from the detailed description of the accompanying drawings.